1. Field of the Invention
The present invention relates to a piezoelectric generating apparatus constructed by using a piezoelectric ceramics element.
2. Description of the Related Art
A piezoelectric material has a variety of applications as a transducer between a mechanical energy and an electrical energy. A large number of materials of both inorganic matter and organic matter are known as a material, which represents a piezoelectric effect, and a piezoelectric ceramics such as PZT (lead zirco-titanate) is a material of currently available in practical use.
The piezoelectric ceramics element is a device having a piezoelectric property caused by applying a DC (direct current) high voltage to a polycrystal so as to produce a residual polarization. Since the piezoelectric ceramics element can vary a basic piezoelectric constant depending on composition, the piezoelectric ceramics element has a wide utilization. The piezoelectric ceramics element of lead zirco-titanate ceramics, especially, has a wide choice range of a composition ratio and a additive and has a variety of application.
FIG. 7 is an illustration of a conventional piezoelectric generating apparatus. This piezoelectric generating apparatus is constructed by a substrate 32 of an acrylic material or the like joined with a piezoelectric ceramics element plate 31, and fixing both end sections of the substrate 32 with a holder 33 made from a hard material such as a metal. Then, a ball 35 made of steel is dropped on the piezoelectric ceramics element plate 31 so as to apply a mechanical impact energy by collision onto the piezoelectric ceramics element plate 31, and a flexural vibration is energized on the piezoelectric ceramics element plate 31 including the substrate 32, thereby picking up an electrical energy.
In spite of the piezoelectric ceramics element of the PZT above described is expected for a practical use, an amount of generated power is little. Therefore, it is a problem that the piezoelectric ceramics element lacks a practical use. Since the substrate 32 and the piezoelectric ceramics element plate 31 are different materials, it is difficult to locate a center of vibration (a position where it does not expand and contract) at a junction surface of the substrate 32 and the piezoelectric ceramics element plate 31. If the center is appeared in the piezoelectric ceramics element plate 31, an efficiency of generation is degraded by producing a cancellation on dielectric polarization.
In view of the above, the present invention has been attained and an object thereof is to provide a piezoelectric generating apparatus having an excellent generating efficiency with simplified structure.
Another object of the present invention is to provide a piezoelectric generating apparatus having an excellent generating efficiency, which is capable of improving remarkably generating efficiency of the piezoelectric generating apparatus having such a single layered structure, thereby simplifying the structure of such the piezoelectric generating apparatus, making compact so as to be able to utilize in multipurpose, and manufacturing at a low cost.
For solving the technical problem, according to a first aspect of the present invention, there is provided a piezoelectric generating apparatus comprising a piezoelectric ceramics plate formed by two plate-shaped piezoelectric ceramics elements which are layered and joined to each other with inverse polarization, in which electricity is generated by beating at least one surface of the piezoelectric ceramics plate.
In the above aspect, since such a structure is employed that a piezoelectric ceramics plate is formed by two plate-shaped piezoelectric ceramics elements which are layered and joined to each other and it is beat to generate electricity, an effect of obtaining a piezoelectric generating apparatus having an excellent generating efficiency and effective for a small power generation is achieved.
According to a second aspect of the present invention, there is provided a piezoelectric generating apparatus comprising a piezoelectric ceramics plate formed by two plate-shaped piezoelectric ceramics elements which are layered and joined to each other with inverse polarization, and cushion material joined to a center of one surface of the piezoelectric ceramics plate, in which electricity is generated by beating the other surface of the piezoelectric ceramics plate.
According to a third aspect of the present invention, there is provided a piezoelectric generating apparatus comprising a piezoelectric ceramics plate formed by two plate-shaped piezoelectric ceramics elements which are layered and joined to each other with inverse polarization, and cushion material for supporting both ends of the piezoelectric ceramics plate, respectively, in which electricity is generated by beating at least one surface of the piezoelectric ceramics plate.
According to a fourth aspect of the present invention, there is provided a piezoelectric generating apparatus comprising two of the piezoelectric ceramics plates, each joined with the cushion material according to the second aspect, arranged facing each other and further comprising a hard beater provided between the piezoelectric ceramics plates and moved back and forth between the piezoelectric ceramics plates so as to beat each of the piezoelectric ceramics plates.
According to fifth aspect of the present invention, there is provided a piezoelectric generating apparatus comprising the piezoelectric ceramics plate supported and arranged by the cushion material according to the third aspect, and further comprising a hard beater provided on at least one side of the piezoelectric ceramics plate and moved back and forth in the interval with the piezoelectric ceramics plate so as to beat the piezoelectric ceramics plate.
In the second to fifth aspects, since the structure that layered piezoelectric ceramics plates is supported by the cushion material is employed, vibration of the piezoelectric ceramics plates is maintained for a long time and therefore generating efficiency is improved.
Additionally, according to a sixth aspect of the present invention, there is a piezoelectric generating apparatus according to any one of the first to fifth aspects, wherein the two piezoelectric ceramics elements are formed in the same shape. In this aspect, since the layered piezoelectric ceramics plates is formed by using piezoelectric ceramics plates having coincident form, the expansion and the contraction of piezoelectric ceramics elements are performed suitably, therefore generating efficiency is more improved. According to a seventh aspect of the present invention, there is a piezoelectric generating apparatus according to any one of the first to sixth aspects, wherein the piezoelectric ceramics plate has a protector plate attached to on a beat portion, and electricity is generated by beating the protector plate. In this aspect, since the protector plate is attached to the beat portion of the piezoelectric ceramics plates, the piezoelectric ceramics plates is effectively protected against beating.
According to an eighth aspect of the present invention, there is provided a piezoelectric generating apparatus according to any one of the first to seventh aspects, wherein each of the two piezoelectric ceramics elements is formed by joining a plurality of piezoelectric ceramics elements and in layered manner. In this aspect, since each of the piezoelectric ceramics elements is used in a layered junction form, the strength of the piezoelectric ceramics element is maintained effectively. According to a ninth aspect of the present invention, there is provided a piezoelectric generating apparatus according to any one of the first to eighth aspects, wherein material of lead zirco-titanate ceramics is used as the piezoelectric ceramics element. In this aspect, since the material of lead zirco-titanate ceramics is used as the piezoelectric ceramics element, application field as a generating apparatus becomes wide and effective In practical use.
According to a tenth aspect of the present invention, there is provided a piezoelectric generating apparatus comprising a piezoelectric ceramics body formed by joining a piezoelectric ceramics element with a metal plate, capable of generating electricity by applying a collision load to the piezoelectric ceramics element or the metal plate, which is a technical precondition, wherein a structure makes an amount of a distortion of the metal plate being balanced with that of the piezoelectric ceramics element by adjusting a thickness of the metal plate, and sets a center point of vibration, in condition that the piezoelectric ceramics element and the metal plate are joined, at a junction boundary surface of the piezoelectric ceramics element and the metal plate.
In the tenth aspect, since the structure makes an amount of a distortion of the metal plate being balanced with that of the piezoelectric ceramics element by adjusting a thickness of the metal plate, and sets a center point of vibration, in condition that the piezoelectric ceramics element and the metal plate are joined, at a junction boundary surface of the piezoelectric ceramics element and the metal plate, the generating efficiency is improved remarkably, the generating apparatus having outstanding generating efficiency effective for a small power generation can be obtained, and making compact and manufacturing at a low cost can be achieved, because the number of the parts is reduced.
According to an eleventh aspect of the present invention, there is provided a piezoelectric generating apparatus according to the tenth aspect, wherein the ceramics body is supported by a cushion member.
In the eleventh aspect, since the structure that the ceramics body is supported by cushion material, is employed, the vibration of the piezoelectric ceramics body is maintained for a long time, and thereby generating efficiency is improved.
According to a twelfth aspect of the present invention, there is a piezoelectric generating apparatus according to the tenth or eleventh aspect, further comprising a protector plate stuck on a beat surface of the piezoelectric ceramics body and thereby durability can be improved.
In the twelfth aspect, since a protector plate is adhered to a beat surface of the ceramics body, the piezoelectric ceramic device is effectively protected from the collision load of the piezoelectric ceramics body.
According to thirteenth aspect of the present invention, there is a piezoelectric generating apparatus according to any one of the tenth to twelfth aspects, wherein the piezoelectric ceramics element is formed of materials of lead zirco-titanate ceramics.
In the thirteenth aspect, the material formed of lead zirco-titanate ceramics is utilized as the piezoelectric ceramics element, the application field as the generating apparatus is widened and the generating apparatus is effective for the practical use.